As automobiles have become more and more intelligent, the demand for automobiles which can be more comfortably driven has led to the installation of various electronic apparatuses. In particular, vehicle navigation systems (hereinafter referred to simply as “navigation systems”) that guide an automobile to a destination in an unknown area without becoming lost or using a map have become very popular. Recent navigation systems not only guide an automobile to a destination through the shortest route, but many have multiple functions for providing a variety of information to enhance the driving experience. For example, many navigation systems in practical use not only provide information on recommended routes using real-time traffic information, such as information on traffic snarl-up and closure, in order to guide the automobile to a destination, but also provide information on recommended facilities (for example, amusement facilities, popular restaurants, beauty spot, and so on) near or along a route to a destination.
Operating such a navigation system is commonly performed using a special remote control unit or through a keyboard or joystick provided near the driver's seat. There are also navigation systems with touch panel buttons on the display screen that allow the user to operate the system by selecting among sequentially displayed items. In the following description below, all of the operation types described above are collectively referred to as “manual input type”. In addition, recent progress in the voice recognition technology has made it possible for users to operate navigation systems using voice commands. A user of this type of navigation system performs necessary input operations in response to voice guidance messages from the navigation system. Hereafter, this type of input is referred to as “voice input type”.
Conventionally, both the manual input type and the voice input type require the user to perform operation in a predetermined order to display desired information.
However, for a user to receive various types of additional information (information on recommended routes and recommended facilities) as described above, it is necessary to select necessary information from a vast amount of information. That is, the user must enter necessary multiple conditions for information selection.
In general, when a car is parked, it is possible for the driver to perform multiple input operations for searching a route because no problem is presented by the driver concentrating on the operation of the navigation system. However, when the car is in motion, it is not recommended that the driver frequently perform operations other than driving. For this reason conventional navigation systems commonly impose restrictions on their operation which prevent a driver from performing manual input operation while viewing the display. As such, a problem with present manual input type navigation systems is that the user cannot operate the system while the car is in motion. Another problem with a manual input type navigation system is that an input operation begun while the car was idling, such as while waiting at a stoplight, is forcibly suspended when the user resumes driving, and therefore the operation cannot be performed continuously and the operability is decreased.
On the other hand, a voice input type navigation system, in which the user responds to voice guidance messages, does not require the user to continuously view the display, and allows the user to perform input operation of the navigation system even during driving. However, speech recognition systems are unable to accept voice commands, even when previously defined, unless the command is given in a specific situation. If an appropriate voice command is not entered, the navigation system repeatedly outputs the same voice guidance message, and errors not uncommonly result. That is, operating a navigation system through voice input requires training and therefore there is a problem that use of a high functionality navigation system is undesirably complicated or difficult.
In addition, various background noises inside or outside of a car can impede the accuracy of voice recognition, sometimes resulting in voice recognition errors. Although some conventional navigation systems allow for both manual input and voice input, none of those systems allow input to be switched between manual input and voice input during operation. That is, a user having difficulty using voice input and wishing to switch to manual input is forced to repeat the operation from the beginning. This makes the system difficult to use.
The present invention seeks to solve the problems associated with the art described above. It is an object of the present invention to provide a navigation system that allows the user to smoothly and continuously perform a desired navigation search whether the vehicle is parked or is in motion and whether the input is of a manual input type or voice input type.